Pipe Nipple

A pipe nipple is a straight section of pipe—typically steel, brass, or PVC—threaded on both ends, sized from close nipple (barely any unthreaded body) up to 6 inches or longer depending on the application. The threads are cut to standard NPT (National Pipe Thread) dimensions, and the nipple itself is measured by nominal pipe size and length.

In the field, nipples are the go-to connector for joining two female-threaded fittings when you need a rigid, permanent joint. Common uses include connecting a water heater to supply lines, mounting faucets to a pedestal sink, or building out manifolds and rough-in setups where you're threading into elbows, tees, or valve bodies. They come in galvanized steel for water service, brass for better corrosion resistance and appearance, and plastic for low-pressure drainage or certain chemical applications.

Size the nipple to your fitting size and allow enough body length so threads don't bind—a close nipple (nearly all thread) is necessary only when space is tight. Over-tightening a nipple into brass or plastic fittings will crack them; hand-tight plus one wrench turn is usually the limit. Always use thread seal tape or compound on male threads to prevent leaks.